package binarytree;

import java.util.Arrays;

public class ArrBinaryTreeDemo {
    public static void main(String[] args) {
        int[] arr = {1, 2, 3, 4, 5, 6, 7};
        ArrBinaryTree arrBinaryTree = new ArrBinaryTree(arr);
        arrBinaryTree.preOrder();
        arrBinaryTree.infixOrder();
        arrBinaryTree.postOrder();
    }
}

class ArrBinaryTree {
    private int[] arr;

    public ArrBinaryTree(int[] arr) {
        this.arr = arr;
    }

    public void preOrder() {
        this.preOrder(0);
    }

    private void preOrder(int index) {
        if (arr == null || arr.length == 0) {
            System.out.println("数组为空，不能前序遍历");
            return;
        }
        System.out.println(arr[index]);
        if (index * 2 + 1 < arr.length) {
            preOrder(index * 2 + 1);
        }
        if (index * 2 + 2 < arr.length) {
            preOrder(index * 2 + 2);
        }
    }

    public void infixOrder() {
        this.infixOrder(0);
    }

    private void infixOrder(int index) {
        if (arr == null || arr.length == 0) {
            System.out.println("数组为空,不能中序遍历");
            return;
        }
        if (index * 2 + 1 < arr.length)
            infixOrder(index * 2 + 1);
        System.out.println(arr[index]);
        if (index * 2 + 2 < arr.length)
            infixOrder(index * 2 + 2);
    }

    public void postOrder() {
        this.postOrder(0);
    }

    private void postOrder(int index) {
        if (arr == null || arr.length == 0) {
            System.out.println("数组为空，无法后序遍历");
            return;
        }
        if (index * 2 + 1 < arr.length)
            postOrder(index * 2 + 1);
        if (index * 2 + 2 < arr.length)
            postOrder(index * 2 + 2);
        System.out.println(arr[index]);
    }


}